JPH0472022A - Method and device for controlling strip temperature in continuous annealing furnace - Google Patents

Abstract

PURPOSE:To secure the quality of a steel strip, to minimize flow rate of fuel and to stabilize the operation by executing feedback control while continuously and immediately predicting future strip temp. and furnace temp. at the time of varying the prescribed period and center velocity at not only time of changing set of the steel strip, but also in the steel strip, in continuous casting of the steel strip. CONSTITUTION:This invention is related to the strip temp. controlling method for controlling the steel strip temp. at outlet of a heating furnace by changing the flow rate of fuel in the heating furnace as the operation variable at the time of changing (resetting) strip thickness, strip width and temp. reference at the outlet of heating furnace (strip temp. reference) or changing center line velocity and/or in the fixed period in a coil, in the continuous annealing furnace for executing the continuous annealing by continuously passing the steel strip having different strip thickness, strip width or temp. reference at the outlet of heating furnace, in the heating furnace. That is, the strip temp. from the present to the future is continuously predicted and/or the furnace temp. from the present to the future is continuously predicted and deviation between the aimed strip temp. and the predicted strip temp. and/or deviation between the aimed furnace temp. and presumed furnace temp. and the flow rate of fuel for optimizing the prescribed evaluation function with variation in the flow rate of fuel in the heating furnace are calculated to suitably control the temp. of steel strip at the outlet in the heating furnace.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a continuous annealing furnace in which strips having different thicknesses, widths, or heating furnace outlet temperatures are continuously passed through a heating furnace for continuous annealing. The present invention relates to a plate temperature control method and device.

In addition, - Continuous annealing furnaces for boat fishing include a heating furnace for heating cold-rolled steel sheets, a soaking furnace for maintaining the steel sheets coming out of the heating furnace at a predetermined temperature, and a cooling furnace for cooling the steel sheets. The furnaces are arranged in parallel along the transport path of the steel sheet and constitute one continuous annealing treatment line, but the sheet temperature that is the object of control in the present invention is the sheet temperature at the outlet of the heating furnace, and therefore, the main text In the above, the term "plate temperature" or "furnace temperature" refers to the plate temperature at the outlet of the heating furnace or the temperature inside the heating furnace.

[Conventional technology] Conventional technology related to plate temperature control methods and devices for continuous annealing furnaces is a preset method in which manipulated variables (fuel flow rate, set furnace temperature, center line speed, etc.) are changed at an appropriate timing during the set period. (Unexamined Japanese Patent Publication No. 61-113728.62-146
225, etc.), and sampling control that estimates or predicts the plate temperature every moment and changes the manipulated variables (fuel flow rate, set furnace temperature, center line speed, etc.) (Japanese Patent Laid-Open No. 61-19
0026.63-307223, etc.), or a zone load adjustment method that controls the plate temperature at the outlet of the heating 7 furnace by devising the fuel load distribution and operation variable setting timing of the heating zone (zone) that constitutes the heating furnace (Japanese Patent Application Laid-Open No. Showa 62-222030.6
1-30629 etc.).

[Problem to be solved by the invention] The problems with the conventional technology mentioned in the previous section will be described below.

First, in the preset control method, the manipulated variable is only set according to the value obtained by preset calculation, and feedback control cannot be performed until the set change is completed. In other words, once the manipulated variable is set by preset calculation, even if a control error occurs due to an error in the preset model itself or disturbances such as plate thickness or speed, it cannot be corrected, and the plate temperature will not be corrected until the set change is completed. It simply continues as it occurs. Therefore, even if, for example, the plate temperature changes for some reason, the operation amount cannot be changed, resulting in defects such as heat buckles in the strip, which may cause operational troubles in the continuous annealing furnace.

Next, the sampling control method solves the problem of the preset control method mentioned above, but in the calculation to obtain the manipulated variable from moment to moment in a predetermined sampling period, the future plate temperature prediction value is only calculated at one point. Therefore, there is a haze point where calculation of the target plate temperature trajectory becomes complicated.

In addition, a common problem with both preset control methods and sampling control methods is that there are many cases in which the center line speed is used as the manipulated variable, which is a problem in reality. There are many. This is because the center line speed setting value is determined only by the heating furnace capacity, but in reality the center line speed is determined not only by the capacity of the heating furnace but also by the strip threading conditions at the line entrance and exit. This is because predictions of plate temperature changes due to speed changes will no longer match the actual plate temperature, resulting in a decrease in control accuracy, as it is influenced by linear events. Namely.

Center line speed setting is effective when the line operating conditions from the inlet side to the outlet side are very stable, but in reality, line speeds often fluctuate due to other factors due to changes in operating conditions. , speed setting cannot be said to be appropriate as an operating end for plate temperature control.

Finally, I would like to talk about the problems that are common to preset control methods, sampling control control methods, and zone load adjustment control methods.First of all, the fuel flow rate load balance of the zones that make up the heating furnace The furnace temperature in a certain zone may become high depending on the characteristics/capabilities of the individual zones, etc., which may shorten the life of the heater (radiant tube in radiation terms) or, in the worst case, cause equipment damage such as melting.

However, this is not the case when the furnace temperature for each zone is set as the manipulated variable for control, but it can be said to be a serious problem in a method that sets the average furnace temperature or fuel flow rate. Conventionally, this problem has often been solved by adding some ingenuity to the fuel flow load distribution for each zone, or reducing the fuel flow rate when the furnace temperature approaches the upper limit. Like plate temperature, this characteristic has delays such as dead time and time constant, and conventional measures that do not take into account the dynamic characteristics of furnace temperature cannot be said to be sufficient. Second, for example, JP-A-61-
190026, there is a control method that aims to improve control accuracy by sequentially identifying and adaptively modifying the parameters of the control model equation, but conventional methods are based on the temperature reference level (heat cycle) at the outlet of the strip heating furnace. Because the type of strip classification is not taken into account, depending on the product mix (ratio of strip production by type), the parameters of the model equation may be biased toward heat cycles with a large amount of sheet passing, and heat cycles with a small amount of sheet passing. This means that sufficient parameter estimation accuracy cannot be obtained for cycles or types, and control accuracy deteriorates.

The present invention has been devised to solve the conventional problems described above, and it is possible to control the heating furnace plate by controlling the fuel flow rate when changing the set or changing the center line speed and/or at a constant cycle in the coil. This paper proposes a method and device for controlling the plate temperature of a heating furnace, which controls the temperature and prevents the furnace temperature from exceeding the upper limit for each zone, and which has good control accuracy even in heat cycles with a small number of plate threads or a type of heat cycle. be.

[Means for Solving the Problems] The gist of the present invention is 1. In a continuous annealing furnace in which strips having different plate thicknesses, plate widths, or heating furnace exit temperature standards are continuously passed through a heating furnace to perform continuous annealing, When changing the plate thickness, plate width, heating furnace outlet temperature standard (plate temperature standard) (replacing the set), or changing the center line speed, and/or changing the fuel flow rate of the heating furnace as a manipulated variable at a constant cycle in the coil. A plate temperature control method for controlling the furnace outlet strip temperature (plate temperature), which continuously predicts the plate temperature from the present to the future and/or continuously predicts the furnace temperature from the present to the future, and The plate temperature is controlled by calculating the fuel flow rate that optimizes a predetermined evaluation function based on the deviation between the temperature and the predicted plate temperature and/or the deviation between the target furnace temperature and the predicted furnace temperature and the amount of variation in the fuel flow rate of the heating furnace. A continuous annealing furnace plate temperature control method characterized by:

2. When determining the set value of the fuel flow rate, the weight of the deviation between the target plate temperature and the predicted plate temperature of the predetermined evaluation function and the weight of the deviation between the target furnace temperature and the predicted furnace temperature are continuously determined based on the value of the actual furnace temperature. The continuous annealing furnace plate temperature control method according to claim 1, characterized in that the plate temperature and/or the furnace temperature is controlled by changing the plate temperature.

3. Parameters in the control model are estimated by changing estimation weights depending on the heating furnace outlet temperature reference level (heat cycle) of the strip and/or a type of strip. The continuous annealing furnace plate temperature control method described.

4. In a continuous annealing furnace where strips with different plate thicknesses, plate widths, or heating furnace outlet temperature standards are continuously passed through the heating furnace for continuous annealing, these plate thicknesses, plate widths, and heating furnace outlet temperature standards (plate temperature Continuously predicts the plate temperature from the present to the future when changing the standard (standard) or changing the center line speed and/or at a constant cycle within the coil, and/or continuously predicts the furnace temperature from the present to the future. The heating A plate temperature control device that controls the furnace exit strip temperature (plate temperature), which includes a set change detector that detects whether the strip is set, a speed detector that detects the strip passing speed, and a temperature of the heating furnace. A detector group comprising a furnace temperature detector and a plate temperature detector for detecting the temperature of the strip in the furnace 80, and a set change position of the strip according to output signals from the set change detector and speed detector. Strip tracking means to constantly track and determine current and future thickness, width and furnace exit temperature standards.

Strip specifications (
strip specification setting means for specifying the strip thickness, strip width, and furnace exit strip temperature standards) in advance;

Plate temperature control that controls the plate temperature by calculating the fuel flow rate that optimizes the evaluation function based on the deviation between the target plate temperature and the predicted plate temperature and/or the deviation between the target and predicted furnace temperature and the variation amount of the fuel flow rate. A continuous annealing furnace plate temperature control device comprising: a means for controlling a fuel flow rate based on an output signal from the plate temperature control means; and a means for estimating parameters of a prediction model for plate temperature and furnace temperature. .

That is, in order to solve the above-mentioned problems, the present invention first uses a known plate temperature prediction model that predicts plate temperature from furnace temperature, fuel flow rate, plate thickness, plate width, and center line speed (hereinafter abbreviated as center speed). We also provide a zone furnace temperature prediction model that predicts the furnace temperature for each zone (hereinafter referred to as zone furnace temperature) from the fuel flow rate, plate thickness, plate width, and center speed. This model allows continuous prediction of plate temperature and zone furnace temperature from the present to the future. The strip set change position is constantly tracked, and the actual values of strip temperature, zone furnace temperature, fuel flow rate, strip thickness, strip width, and center speed are sampled at predetermined intervals. input into the temperature prediction model. In addition, the value of the center speed is constantly monitored, and if a change exceeding a certain value occurs, the actual values of the sheet temperature, zone furnace temperature, fuel flow rate, sheet thickness, sheet width, and center speed are immediately taken in to predict the sheet temperature. model and zone furnace temperature prediction model. In this way, by immediately taking in the above-mentioned performance data at predetermined intervals and when the central speed changes, it is possible to constantly predict the plate temperature and zone furnace temperature from the present to the future.

Next, an evaluation function is created that continuously evaluates the deviation between the target plate temperature and the predicted plate temperature and/or the deviation between the target furnace temperature and the predicted zone furnace temperature and the amount of fluctuation in the fuel flow rate of the heating furnace from now to the future. The plate temperature is controlled by calculating and setting a fuel flow rate that optimizes the evaluation function.

According to the present invention, the target plate temperature and the predicted plate temperature and/or the target furnace temperature and the predicted zone furnace temperature from the present to the future are naturally and continuously incorporated into the control calculation, and when a change in the center speed occurs, the control is immediately performed. For example, as seen in Japanese Patent Laid-Open No. 61-190026, the calculation of the target plate temperature that occurs when the future plate temperature prediction value is only one point and the center speed is defined as the manipulated variable. Complexity (optimization of center speed change timing and associated moment-by-moment calculation of target plate temperature trajectory) can be avoided. The method for determining the target plate temperature near the set change in the present invention will be described using Fig. 2. As shown by the solid line in the figure, normally the plate temperature at the furnace outlet of the preceding strip is changed from the plate temperature at the furnace outlet of the trailing strip. It is sufficient to simply change the plate temperature standard in a stepwise manner, but as shown by the broken line in the figure, there is a large difference between the furnace exit plate temperature standards for the front and rear strips, and there are concerns that the plate temperature may be outside the upper and lower limits and the fuel flow rate may fluctuate excessively. For example, when transitioning from low-temperature material to high-temperature material in order to aim for the safety of the strip material, the plate temperature standard should be gradually changed to the high-temperature material starting near the rear end of the low-temperature material according to a predetermined rate of change. On the other hand, when transitioning from high-temperature material to low-temperature material, it is sufficient to gradually change the plate temperature standard to the low-temperature material according to a predetermined rate of change from the tip of the low-temperature material. In addition, even if the furnace outlet plate temperature standards for the leading and trailing strips are the same, if the plate thickness changes significantly, for example, as shown by the dotted line in the figure, the actual plate temperature changes near the set change point. By making fine adjustments to the target plate temperature on the safe side, unnecessary fluctuations in fuel flow rate can be prevented. As described above, according to the present invention, the target plate temperature can be set relatively easily, and good control can be realized even with changes in conditions such as changes in the center speed and changes in the plate thickness.

In addition, if only the deviation between the target plate temperature and the predicted plate temperature and the amount of variation in fuel flow rate are considered in the evaluation function (the weight of the deviation between the target furnace temperature and the predicted zone furnace temperature is set to zero), a simple For plate temperature control, if only the deviation between the target furnace temperature and the predicted zone furnace temperature and the amount of variation in fuel flow rate are considered in the evaluation function (the weight of the deviation between the target plate temperature and the predicted plate temperature is set to zero) Since the furnace temperature control is simple, the present invention includes these simple plate temperature control and simple furnace temperature control. By setting the weight of the flow rate fluctuation to zero, it is possible to achieve very responsive plate temperature control and furnace temperature control.

In addition, as shown in Figure 3, the target furnace temperature in the evaluation function is set slightly smaller than the upper limit of the zone furnace temperature, and the weight of the deviation between the target plate temperature and the predicted plate temperature is set to the actual zone furnace temperature. By gradually decreasing the weight of the deviation between the target furnace temperature and the predicted zone furnace temperature as it approaches the upper limit, and conversely increasing the weight of the deviation between the target furnace temperature and the predicted zone furnace temperature as it approaches the upper limit of the zone furnace temperature, it is possible to prevent the actual zone furnace temperature from exceeding the upper limit. can. That is, as the zone furnace temperature approaches the upper limit, plate temperature control gradually transitions smoothly to zone furnace temperature (rise prevention) control. Additionally, regarding the prediction of zone furnace temperature, the zone furnace temperature may be predicted for all individual zones, or may be predicted for a zone that will be a bottleneck depending on the characteristics of each individual furnace, Alternatively, similar control can be performed by predicting the weighted average value of the furnace temperature in each zone (giving a larger weight to the zone that is the bottleneck). In this sense, it will be simply referred to as furnace temperature from now on for simplicity.

Finally, when performing adaptive correction of the parameters in the plate temperature prediction model and furnace temperature prediction model, known parameter estimation methods such as the fixed trace method, exponentially weighted least squares method, or sequential least squares method with forgetting coefficient are used. However, in the case of a sheet temperature prediction model, the parameter estimation accuracy is sufficient for heat cycles with a large number of sheets to be passed through, or for heat cycles with a small amount of sheets to be passed, or for one type of heat cycle where the parameters of the model formula are biased toward one type. In order to prevent this, the heat cycle or type of estimation weight with a small amount of sheet passing should be increased, and conversely, the heat cycle or type of estimation weight with a large amount of sheet passing should be made small. A specific method for determining the estimated weight may be, for example, determined in inverse proportion to the production amount.

Furthermore, the present invention also provides an apparatus for implementing the control method as described above. The control device according to the present invention includes a set change detector that detects the set litho of the strip, a speed detector that detects the strip passing speed, a furnace temperature detector that detects the temperature of the heating furnace, and a temperature of the strip at the furnace outlet. A group of detectors equipped with a plate temperature detector that detects the current and future plate thicknesses and strips are constantly tracked in response to output signals from the set change detector and speed detector. A strip tracking means that determines the width and furnace exit plate temperature standard, and strip specifications (thickness, plate width, furnace exit plate temperature standard) based on a predetermined strip running schedule.
A strip specification setting means that specifies the strip temperature in advance and the above-mentioned plate temperature and furnace temperature prediction model based on this predicted value are used to continuously predict the future plate temperature and furnace temperature, and immediately when the predetermined period and center speed change. Calculate the fuel flow rate to optimize the evaluation function that continuously evaluates the deviation between the target plate temperature and the predicted plate temperature and/or the deviation between the target furnace temperature and the predicted furnace temperature and the amount of variation in the fuel flow rate. It has a plate temperature control means for controlling, a fuel flow rate control means for controlling a fuel flow rate based on an output signal from the plate temperature control means, and a parameter estimating means for a predictive model of plate temperature and furnace temperature.

[Embodiments] Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the overall configuration of a plate temperature control system according to the present invention, and the present invention will be described in detail with reference to this first.

Among the signal lines shown in the figure, solid lines indicate data flow, and dotted lines indicate detection pulses or activation signals. Incidentally, the present invention is actually controlled using a process computer, and the first
The figure clearly shows the internal functions. While passing through the heating furnace 102, the cold-rolled strip 100 is reciprocated vertically many times by a hearth roll 104.
In the meantime, a heater (generally composed of a radiant tube, hereinafter referred to as a radiant tube) 106
heated by. Strip 10 exiting furnace 102
0 is sent to the next soaking furnace (not shown).

The object to be controlled in the present invention is the temperature (plate temperature) of the strip 100 at the furnace outlet, and the plate temperature is made to follow the target plate temperature by manipulating the fuel flow rate of the furnace. Since the strip 100 is heated by radiant heat from the radiant tube 106, the plate temperature can be controlled by controlling the flow rate FL of coke oven gas (COG) as the heat source of the radiant tube 106, for example.

The fuel flow rate FL to the radiant tube 106 is detected by a known fuel flow rate detector 13, and the fuel flow rate controller 10
controlled by The plate threading speed (=center speed) (2) is detected by a known speed detector 11.

The controller 10 uses a control method used in boat fishing, such as proportional-integral-derivative (PLD) control.

The key point of the invention is how to determine the set point to the fuel flow controller 10 at a given period and at a median speed change. First, the strip tracking device 6 detects the detection pulses PL, P, 2 from the set change point detectors 19 disposed at the inlet and outlet of the furnace, the threading speed (2) detected by the speed detector 11, and the strip length (one point of the strip).
0 strip length (that is, the length from the preceding set point to the subsequent set point) The starting signal P3 is outputted to the parameter estimator 9 and the plate temperature controller 8, and the starting signal P3 is outputted to the strip specification setting device 1 at the timing when the set approval passes through the eight openings of the heating furnace. The strip specification setting device 1 is activated by a signal P3 from the strip tracking device 6, and sets the strip specification (thickness TRI, TH2; strip width WDI, WD2; total strip length L; heating furnace exit plate temperature reference = target plate temperature TSRI,
TSR2) is output. Here, the subscript 1 in the strip specification is a value related to the strip passing through the heating furnace outlet,
Subscript 2 is the value for the subsequent strip after set change. Next, the plate temperature follow-up controller 8 performs feedback control of the plate temperature, and is activated immediately at a predetermined control cycle and when the central speed changes. The fuel flow rate observation value FL from the detector 13, the plate temperature observation value TS from the plate temperature detector 14 at the furnace outlet, and the target plate temperature TSR are inputted, and the fuel flow rate set value FLS is calculated, and the fuel flow rate is controlled. Output to device IO. The fuel flow controller 10 may be, for example, a flow control valve.

In the above, the plate temperature tracking controller 8 uses a known plate temperature prediction model (for example, a special Kaisho 61-19
According to 0026), it has a furnace temperature prediction model that expresses the dynamic relationship between the furnace temperature, fuel flow rate, plate thickness, plate width, and speed as described below.

In addition, a known parameter estimator 9 (for example, Japanese Patent Laid-Open No. 61-1
90026) is started at a predetermined period and estimates the parameters in the plate temperature prediction model and furnace temperature prediction model based on past performance data.

(Furnace Temperature Prediction Model) The above-mentioned furnace temperature prediction model used in the present invention is a model that is discretized with respect to time using the sampling period (control period) as a unit of time, and is defined by the following equation.

y'(t+d=alXy'(t)+blXu(t)+
b2Xu(t-1)+-+bmXu(t-m+1)+c
lXW(t+1)+-+cdXW(t+d')+e ・
---(1) The model equation expressed by equation (1) is based on the current furnace temperature, the fuel flow rate from the current time until the past m sampling, the plate thickness, plate width, and speed from the current time until the dead time. The predicted value is used to predict the furnace temperature ahead of the dead time.

In the above formula, u (t) = F L (t) - F L ・=
(2) W(t)=WD(t)XTH(t)XVS(t
)−WTV・(3):y′(t)=T F
(t)-T F...(4)VS(t)=(flXV(
t)+f2XV[t-1)+-+f], XV(t-1+
1))/(fl+f2+・+fl L=(5) where, t: Sampling time d': Control dead time between fuel flow rate and furnace temperature U: Manipulated amount in model (fuel flow rate) y': Model Controlled variable (furnace temperature) at y I: Predicted value of y + m: Order of u FL: Fuel flow rate FL: Average value of fuel flow rate in normal operation 1゛F:
Furnace temperature TF2 Average value of furnace temperature in normal operation TH: Furnace outlet plate thickness Wl): Furnace outlet plate width S: In-furnace speed V at point P on the strip passing through the furnace outlet: Median speed WTV: W D X T HX V during normal operation
Using a model with an average value of S or more, plate temperature follow-up control of the heating furnace is performed in the following manner.

(Plate temperature follow-up control) Plate temperature follow-up control is activated immediately at a predetermined period and when the central speed changes, and closed-loop control is performed in which the fuel flow rate, which is the manipulated variable, is calculated every moment. For example, the amount of change in the fuel flow rate is determined by taking the value that gives the minimum value of the evaluation function J as shown below.

j=d j: d + NU + ω3Σ△u (t+ k -1) -- (6) where, r: Target plate temperature y: Predicted plate temperature r' Second furnace temperature y': Predicted furnace temperature ΔU: Manipulated variable change amount d: Control dead time between fuel flow rate and plate temperature N2: Predicted plate temperature time N2': Predicted furnace temperature time NU: Calculation time of fuel flow rate ω1, ω2, ω3: Respectively, The weight of the deviation between the target plate temperature and the predicted plate temperature, the weight of the deviation between the target furnace temperature and the predicted furnace temperature, and the weight of the amount of variation (change amount) in the fuel flow rate of the heating furnace.Here, N2 and N2' are the future values. It represents the time during which the plate temperature and furnace temperature are continuously predicted and the deviation from the target value is evaluated. Also, as mentioned in the previous section, ω1, ω2. By changing the weight of ω3, control with various intentions can be realized. - Shootingly, ω3 is relatively ω1. If it is larger than ω2, the fuel flow rate fluctuation will be small, but the target value followability will be slow. Conversely, if ω3 is relatively smaller than ω1 and ω2, the fuel flow rate fluctuation will be large, but the target value followability will be fast. Become. When determining specific values, we will use preliminary simulations, the characteristics of each heating furnace, operating guidelines, etc.
All you have to do is decide on the initial value and tune it to the optimal value while checking the response when applying it to an actual reactor.

The method for calculating ΔU that gives the minimum value of this evaluation function J is as follows:
For example, Generaliz, a method of modern control theory,
ed Predictive Control The
ory (-film formation predictive control theory), this calculation method is described in various documents and is not directly related to the present invention, so it will be omitted here.

(Parameter Estimation Method) As mentioned previously, known parameter estimation methods such as the fixed trace method, exponentially weighted least squares method, or sequential least squares method with forgetting coefficient may be used. However, in the case of sheet temperature prediction models, the parameters of the model equation are biased toward heat cycles or types with a large amount of sheet passing, and sufficient parameter estimation accuracy may not be obtained for heat cycles or types with a small amount of sheet throughput. Therefore, in order to prevent this, a heat cycle with a small amount of sheet passing or a type of estimation weight is increased, and a heat cycle with a large amount of sheet passing or a type of estimation weight is decreased.1 For example, a sequential minimum with a forgetting factor. One way to use the square method is to change the weight ωi of the evaluation function of the model estimation error as described below using a heat cycle or some other method.

Σω1(yi-yi)2 However, y: Actual plate temperature 8 - y: Moal predicted plate temperature i: Sampling time 1 The method of calculating the parameter that gives the minimum value of the wood cup value function is a known method, and is also described in this book. Since this is not directly related to the invention, it will be omitted.

[Effects of the Invention] As is clear from the above, according to the present invention, the future plate temperature and furnace temperature are immediately and continuously determined not only when the strip set is changed but also when the predetermined cycle and center speed change within the strip. Since feedback control is performed while predicting the temperature, it is possible to obtain high control performance that satisfies the stability and followability of strip temperature and furnace temperature, ensuring strip quality and
This can greatly contribute to minimizing fuel flow and stabilizing operations.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing an embodiment of the plate temperature control device according to the present invention. FIG. 2 is a diagram showing an embodiment of the method for determining the target plate temperature in the present invention. FIG. 3 is a diagram showing a method of setting plate temperature deviation weights, zone furnace temperature deviation weights, and target furnace temperature for preventing zone furnace temperature from exceeding the upper limit value in the present invention. It is. 1... Strip specification setting device, 6... Strip tracking means, 8... Plate temperature tracking controller, 9.
・Parameter estimator, lO...Fuel flow rate controller, 1
1... Speed detector, 12... Furnace temperature detector, 13.
・・Fuel flow rate detector, 14・・Plate temperature detector, 19・
...Set change point detector, 100...Strip,
102... Heating furnace, 104... Hearth roll,
106...Radiant tube. 141rltJ

Claims (1)

[Scope of Claims] (1) In a continuous annealing furnace in which strips having different thicknesses, widths, or heating furnace outlet temperatures are continuously passed through a heating furnace for continuous annealing, these thicknesses, widths, and heating When changing the furnace outlet temperature standard (plate temperature standard) (set change) or changing the center line speed and/or changing the fuel flow rate of the heating furnace as a manipulated variable at a constant cycle in the coil, the heating furnace outlet strip temperature (plate temperature standard) This is a plate temperature control method that continuously predicts the plate temperature from the present to the future and/or continuously predicts the furnace temperature from the present to the future, and calculates the difference between the target plate temperature and the predicted plate temperature. Continuous annealing characterized in that the plate temperature is controlled by calculating a fuel flow rate that optimizes a predetermined evaluation function based on the deviation and/or the deviation between the target furnace temperature and the predicted furnace temperature and the amount of variation in the fuel flow rate of the heating furnace. Furnace plate temperature control method. (2) When determining the set value of the fuel flow rate, the weight of the deviation between the target plate temperature and the predicted plate temperature of the predetermined evaluation function and the weight of the deviation between the target furnace temperature and the predicted furnace temperature are determined based on the value of the actual furnace temperature. 2. The continuous annealing furnace plate temperature control method according to claim 1, wherein the plate temperature and/or the furnace temperature are controlled by continuously changing the plate temperature. (3) Parameters in the control model are estimated by changing estimation weights depending on a heating furnace outlet temperature reference level (heat cycle) of a strip and/or a type of strip. The continuous annealing furnace plate temperature control method described in . (4) In a continuous annealing furnace where strips with different thicknesses, widths, or heating furnace outlet temperature standards are continuously passed through the heating furnace for continuous annealing. Continuously predict the plate temperature from the present to the future when changing the temperature reference (temperature reference) (set change) or changing the center line speed and/or at a constant cycle in the coil, and/or continuously predict the furnace temperature from the present to the future. calculate a fuel flow rate that optimizes a predetermined evaluation function based on the deviation between the target plate temperature and the predicted plate temperature and/or the deviation between the target furnace temperature and the predicted furnace temperature and the amount of variation in the fuel flow rate of the heating furnace; This is a plate temperature control device that controls the strip temperature (plate temperature) at the outlet of the heating furnace, and includes a set change detector that detects the strip set change point, a speed detector that detects the strip passing speed, and a plate temperature control device that controls the temperature of the heating furnace. a detector group comprising a furnace temperature detector for detecting the temperature of the strip and a plate temperature detector for detecting the temperature of the strip at the furnace outlet; and a set change position of the strip according to output signals from the set change detector and the speed detector. strip tracking means to constantly track the strip thickness, width, and furnace outlet temperature criteria to determine current and future strip thickness, strip width, and furnace exit temperature standards;
strip specification setting means for specifying in advance the strip thickness, strip width, and furnace outlet strip temperature standards), and the deviation between the target strip temperature and the predicted strip temperature and/or the deviation between the target and predicted furnace temperature and the fluctuation of fuel flow rate. A plate temperature control means that controls the plate temperature by calculating a fuel flow rate that optimizes the evaluation function based on the quantity; a fuel flow rate control unit that controls the fuel flow rate based on an output signal from the plate temperature control means; A continuous annealing furnace plate temperature control device comprising: means for estimating parameters of a furnace temperature prediction model.